This invention relates to photographic film processing and more particularly, to a method and apparatus for rapid access processing of discrete components of photographic films.
The term "rapid access", as used herein and in the appended claims, is intended to delineate a type of photographic film or film processing which is capable of providing an image on a substrate which has been exposed directly to light defining the image or to which an image is transferred from another image or image facsimile bearing media, by application of a processing fluid layer over the area of the image to be provided. The most common form of rapid access film processing is the diffusion transfer process used in the field of instant photography, and in which a processing fluid is spread over the surface of a sheet or web carried exposed photosensitive emulsion so that the unexposed grains of silver halide in the emulsion layer are transferred to a positive image receiving layer or layer interface. The process has been used extensively for many years to provide positive photographic prints in which the transfer of unexposed grains from the emulsion layer on a negative sheet, for example, is to an image-receiving layer either on a separate positive sheet or incorporated in a photochemical system contained between coextensive opaque and transparent sheets. More recently, positive image transparencies have been developed in which both the photosensitive emulsion layer and the image-receiving layer are carried on a single transparent web or sheet so that upon processing, the transfer occurs between the emulsion layer and the image-receiving layer. Other types of films are known, however, where exposed and unexposed grains or dyes in an emulsion are processed to provide an image without transfer.
Where the rapid access film is initially provided as a strip or web packaged in roll form, such as in presently available slide film systems, processing of the exposed film is usually accomplished as an operation separate from the manipulative steps incidental to exposing and viewing the finished photographic product. Sheet-form films of the type presently used to render a positive photographic print, on the other hand, are processed as an incident to discharging the exposed film from a camera after exposure. To this end, the sheet-form films currently in use are in the nature of preassembled film units in which each unit contains a pod of processing fluid to be distributed completely over the area of photochemicals sandwiched between two sheets of the assembly as the exposed unit is passed to the pressure nip between a pressure roller pair or equivalent. The film units additionally incorporate such structural components as spacing rails between the two sheets to assure precision in the thickness of the processing fluid layer spread over the image receiving area as well as a fluid trap for receiving excess processing fluid supplied with each pod to assure complete coverage of the photochemicals carried over the area of the sheets.
The ultimate cost of each sheet-form photograph obtained using rapid access films and processing in current instant photographic equipment is attributable in substantial measure to the cost of assembling each film unit during manufacture. Such costs, together with either the measure of constraint on print format resulting from an integral assembly of the film unit components or the objections to waste disposal incident to peel-apart film units have compromised the advantages of rapid access photographic prints as against commercially processable conventional films. On the other hand, the photochemistry of rapid access films and film emulsions has progressed to a point where such factors as consistency of color rendition, image resolution and durability of the resulting photograph, both from the standpoint of resistance to physical handling and maintenance of image quality with aging, have enabled the attainment of photographs using rapid access films which are in many respects superior to photographs resulting from conventional laboratory developing procedures. In order for the many desirable attributes of sheet-form rapid access films to be appreciated at lower costs and with a broader range of accommodation to format, a need exists for improvements in the processing and handling of discrete components of a rapid access film systems without preassembly of such components.